In the various construction industries, it is frequently necessary to provide enlarged holes or openings through previously formed walls, wall sections, and the like. These openings, particularly wherein a poured concrete construction is involved, are normally formed by core drills mounted on an appropriate drill stand. Such stand-mounted drills frequently utilize enlarged cylindrical bits to remove a core or plug of material and define an enlarged opening capable of accommodating plumbing, electrical pipes, or the like.
Conventionally, the drill stand will include a mounting bracket with a support bar projecting perpendicularly from the bracket. The support bar accommodates the drill assembly, including the drill motor and drill bit, along with a carriage mounting the drill assembly for longitudinal movement along the support bar.
The drill stand is mounted to a surface in a position generally contemplated to locate the drill bit in alignment with the area to be drilled, designated either by a center point mark on the surface or a center point mark in conjunction with outer markings corresponding to the circumference of the bit. The actual mounting of the stand to the surface is generally affected by a single anchor bolt extending through an elongated slot in the bracket which allows for a physical shifting of the bracket in order to obtain a specific alignment of the bit.
When designating the area to be drilled by only a center point, it will be appreciated that substantial difficulty can be encountered in properly aligning the bit, particularly in those instances when an enlarged tubular core bit is required. The alignment problem can be alleviated, to a degree, by providing peripheral marks corresponding to the periphery of the bit and equi-distant outward from the center point completely thereabout. However, the provision of multiple marks in addition to the center point can lead to errors and can be particularly bothersome when multiple different diameter bits are alternatively used. More importantly, inasmuch as the drill apparatus or assembly can weight anywhere from 40 lbs. to 150 lbs., depending on the size of the bit, an adjustment of the drill stand with the drilling apparatus mounted on the support bar can be a difficult and cumbrous task especially in those instances wherein a hole is to be provided at a point whereat access is difficult or awkward, for example near the ceiling, corners or floor.
An example of a drill stand as discussed above will be noted in U.S. Pat. No. 4,365,418 issued to Hoyss et al on Dec. 28, 1982. This drill stand attempts to overcome centering problems by the provision of a marking element formed as a part of the drill stand base and selectively extended and retracted relative thereto with the drilling apparatus positioned upwardly therefrom on a support column.